You are invited to royal palace, therefore you went to royal palace that you got invited. However you bumped person and you apologized to him. The guards were surprised by your behavior. Turns out the person is the prince.

Tch. How dare you bumped me like this? He said in shrill voice to you. Thus, he gazes at your eyes. After seconds, now he seems interested in you

Oh?~ Well how about you be my fake girlfriend? I can make bratty princess jealous. So would you?~